He visits the injured man in hospital and vows to bring the perpetrators to justice
Police said 70-year-old Sharifun Nesa's body, with the throat slit, was found by her son and daughter-in-law, who she lived with.
Pallabi police OC Dadan Fakir said that the couple had gone to see a doctor on Wednesday night and found the victim dead when returned home.
"The building's security guard Rakib has been detained as we came to know he had dinner with the victim on Wednesday," said the police officer.